1. Field of the Invention
The present invention relates to improvements in a vehicular height controlling arrangement with which a vehicular height is quickly adjusted under a vehicle stopping condition.
2. Description of the Prior Art
It is well known that an automotive vehicle is equipped with a suspension unit adjustable in vehicular height. The vehicular height is automatically lowered with the suspension unit under a stopping condition in order to improve an easiness of a getting on or off. Such a suspension unit is disclosed, for example, in Japanese Patent Provisional Publication No. 58-12816.
Additionally, Japanese Patent Provisional Publication No. 60-4406 discloses a suspension unit in which a damping force is variable in several degrees and a suspension spring coefficient is variable in its value. The suspension unit is adjusted under a stopping condition so that the suspension unit is set to have a large damping force and the suspension spring is set to have a high spring coefficient in order to suppress the swinging of the automotive vehicle caused by the getting on or off of passengers or loads.
Furthermore, Japanese Patent Provisional Publication No. 59-156813 discloses a suspension control system provided with a damper variable in its damping force and an air spring variable in its spring coefficient by controlling a spring coefficient changing valve disposed between the air spring and an accumulator.
However, with such conventional arrangements, a vehicular height is adjusted by supplying or draining driving oil through the damping force selector valve which is set to have a large damping force (a small orifice is selected). Accordingly, when the vehicular height is adjusted under a condition that the suspension cylinder has a large damping force while the vehicle is stopped, it takes a considerably long time to finish the adjusting of the vehicular height. Therefore, it causes a problem that a passenger is required to wait for a time before getting off the vehicle.